A probe has strongly criticised cross-Channel train operator Eurostar for failing to prepare its trains to cope with winter weather that led to breakdowns and mass disruption in December.

Eurostar also had "no plan in place" to deal with the chaos created when five trains broke down in the Channel Tunnel with more than 2,000 passengers aboard in the busy pre-Christmas period.

The maintenance of the trains came in for particular criticism - one of the broken-down trains had no snow screens on its power cars allowing a fine form of snow to cause the electrical systems to fail.

Passengers stuck on the trains endured overflowing toilets and darkness and stuffy conditions for hours on end, the report said, adding that "provision of information to customers was inadequate".

Services were cancelled and disrupted following the breakdowns, throwing the travel plans of thousands of passengers trying to travel between London and Paris and Brussels into disarray.

The poor quality of information offered to passengers waiting to take cancelled or delayed trains was also highlighted.

The study, by former train company boss Christopher Garnett and French civil engineer Claude Gressier, said the weather in northern France on December 18 was "extremely severe with heavy snowfall".

"The review... found that Eurostar trains had not undergone sufficient winter weather preparations to withstand these conditions and that maintenance procedures should be revised," it read.

The first train to break down in the tunnel was recovered "quickly" but "four further trains then broke down in rapid succession and passengers from two of them had to be evacuated onto Eurotunnel passenger shuttles inside the tunnel.

"This was the first time this had happened in 15 years of operation," the review said.

While the evacuations of trains inside the tunnel were carried out "safely and efficiently", the report highlighted concerns about conditions in the trains after they lost air conditioning and lighting.

Eurostar says it will spend more than 30 million pounds ($53 million) upgrading its infrastructure and equipment.